OAKLAND — Fourth-grader Megan Buchanan likes walking to school. “I think it’s fun because you can get your energy out, and it’s really good exercise,” she said as she tromped up a hill Wednesday with her classmates. The 9-year-old Oakland Elementary School student was part of a large group of students, teachers and parents who participated in International Walk and Bike to School Day. Oakland elementary, middle and high school students walked or biked to Oakland High School, gathering in the gym to share a morning snack, participate in a short assembly and enter a raffle for prizes. The younger …